This research proposes to evaluate the changing geographic and demographic structure of U.S. metropolitan migration over the period 1965-1990, and its impact on the populations of metropolitan areas. Its primary focus will be the analysis of internal migration and immigration streams across metropolitan areas and nonmetropolitan territory for the intervals 1965- 70, 1975-80, and 1985-90, using aggregate migration data collected by the decennial U.S. Census. For the 1975-80 and 1985-90 periods, it will examine how the migration patterns of different population subgroups, classed by education attainment, race-ethnicity and gender, respond to the changing geographic structure of metropolitan and nonmetropolitan attractions. This project brings together an interdisciplinary team of demographers, geographers, sociologists, and urban specialists. Its goal will be to show how changing aggregate migration responses have led to shifts in the social demographic structures of metropolitan areas. The underlying premise of our investigation is that the regional restructuring of the nation's metropolitan areas and regions has been occurring in concert with a more segmented migration and redistribution process that will lead to a greater polarization in the social and demographic make-up of areas.